The present disclosure relates to an economical, environmentally-responsible, and highly-portable energy-saving indirect sound capturing acoustic system for non-electronically canceling stereo speaker crosstalk and preventing out-of-sync listening room reflections using the normally non-utilized output from universally-available stereo speakers to also provide real acoustically-pure three-dimensional surround sound to the listener from universally-available two-channel stereo signals without having to electronically manipulate or corrupt the sound signals.
The presented embodiments relate to a low-cost environmentally-responsible indirect sound capturing mostly-portable sound system and non-electronic energy-saving method, for effectively canceling the direct audio sound reproduction problem of stereo speaker crosstalk by using the normally-wasted and non-utilized output from universally-available stereo speakers to add exclusive right and left side sound to the nearest ear of the listener, simultaneously preventing the indirect sound problem of out-of-sync listening room reflections by using the sound controlling components of this sound system to block the uncontrolled broadcast of substantial quantities of normally acoustic damaging indirect sound from traveling out of the sound system, and to provide real acoustically-pure three-dimensional surround sound to the listener from universally-available two-channel stereo signals without having to electronically-manipulate or corrupt the signals.
Supplemental background information has been added in this document because the following system and method of application has been missing from stereo sound reproduction since its inception over eighty years ago. The following background section is presented to help the reader understand cross talk and out-of-sync listening room reflections, how they have affected the audio listener and the stereo sound reproduction industry, and the advantages resulting from eliminating these two problems that may not be immediately apparent even to those skilled in the art.
In large part because of the commercial inability of prior art to substantially and inexpensively solve the above-mentioned two separate stereo audio sound reproduction problems, the pursuit of a high-performance stereo and surround sound experience for the audio consumer has historically been perplexing, time-consuming, expensive, and requiring a highly-disciplined process that has severely restricted the potential benefits to consumers. With this in mind, the following audio consumer needs and expectations is presented below. It applies to audio consumers, commercial sound studios, audio equipment showrooms, music therapy venues, and other high-performance consumers of audio hardware and software. It relates to the purchase, implementation and operation of high-performance audio equipment, with a special emphasis on those audio consumers in pursuit of a high-performance combination of an audio and/or audio-visual system capable of producing a real three-dimensional full-sphere holographic surround sound experience for the listener quickly, easily, dependably, and economically. It is presented for close comparison between the current state of the prior art and the presentation of the following embodiments.
Human Psycho-Acoustic and Brain-Ear Mechanisms Affecting a Realistically-Natural Three Dimensional Surround Sound Experience
It is well known in high-performance sound reproduction circles that one of the most difficult tasks in the acoustic design of sound reproduction is not the simple reproduction of the sound, but the capture and recreation of the sound within a three-dimensional sound field including the realistic horizontal and vertical localization of acoustic objects and events so that they are believably-localized within a three-dimensional holographic sound field that surrounds the listener in a natural way.
An individual can locate sounds in three dimensions—in range (distance), in direction above and below, in direction in front and to the rear, as well left and right on either side of their head. The human auditory system's natural kinesthetic feedback mechanism, including sound localizing head-turning feedback such as slight non-cognizant head movements, even minimum turning or rotating of the head while listening to sounds, provide the listener with important and subtly enhanced sound source kinesthetic feedback that the auditory system and brain use to help pinpoint the sound location. These include three essential psycho-acoustic components of frequency change (including harmonic variation), amplitude change (including starts, stops, and transients) and acoustic directional change (especially in the lateral horizontal plane around a listener). This automatic function of the human psycho-acoustic mechanism gives priority attention to surrounding acoustic movement or acoustic directional change.
For a reproduced surround sound system, therefore, to produce human interest, attention and emotional response to the human brain as a realistically-natural surround sound created within a real three-dimensional space around a listener, especially for the reproduction of a multiplicity of realistically-natural three-dimensional full-sphere holographic audio musical sounds surrounding the listener, it is essential that the above-mentioned fundamental human psycho-acoustic and brain-ear surround sound components also be included as significant reference standards for close comparison between the prior art produced surround sounds and the surround sounds produced by the following embodiments.
Acoustic Damaging Problems Associated with Stereo Audio Sound and Surround Sound Reproduction
Audio sound, including audio or acoustic radiation, is composed of both sound information and sound wave energy emitted from speakers (e.g., individual transducers or transducer drivers including those located on conventional audio sound speakers or other electronic devices).
Both mono and stereo sound is normally emitted by the speakers and projected or dispersed outwardly in all directions from the speaker's sound emission area into a multiplicity of room directions. It has been known for some time that stereo audio signals, including universally-available two-channel stereo audio signals, like audio music recordings and live audio-visual program material, contain three-dimensional surround sound information.
The process whereby original surrounding sound field information can be initially three-dimensionally encoded into two simple signals can be understood conceptually when it is considered that, minimally, the use of just two stereo microphones operate substantially similar to our two ears. That is, a plurality of acoustic information from individual sounds can be simultaneously precision-localized to form a three-dimensional surrounding sound field by mathematical-based progressively time-delayed acoustic directional, amplitude and acoustic distance cues substantially picked-up by the two stereo microphones. Unfortunately for the sound reproduction industry and for the listener, the stereo audio sound signal unlocking and electronic signal reproduction process has been substantially difficult, cumbersome, and exponentially expensive to accomplish since the very beginning of audio sound reproduction eighty year ago. This is largely due to the following problems and limitations.
Stereo audio sound emitted from conventional stereo speakers into a conventional listening room is divided into direct and indirect sound components. Direct sound and indirect sound are emitted together from conventional stereo speakers. Direct sound is a very small percentage, less than 2%, of the speaker's total sound output that travels directly from the speaker, primarily from the tweeter and woofer transducer driver components of the speaker. Indirect sound is all of the rest of the speaker's total emitted mass of sound information and sonic energy. Throughout the history of stereo audio sound reproduction, the speaker's direct sound component has been the most important, the most traditionally-tested, sought-after and compared speaker component value, whereas the indirect sound component has traditionally been viewed and regarded in the exact opposite.
One of the reasons is that indirect sound is considered a nuisance sound because it is heard as corrupted sound. This is because this largest and most substantial indirect sound portion of sound energy, while still in its acoustically-pure state, is allowed to be first projected out into a room in a plurality of directions with little purposeful initial overall control between the speakers and the listener. What normally happens then is that, after being uncontrollably projected out into the listening room, the indirect sound interacting with conventional listening room itself substantially damages the purity of this originally-pure speaker emitted indirect sound component. This is because the room's boundary walls, ceiling, windows, floor, open spaces, the shape and texture of its furnishings, and all the materials and accessories within the listening room corrupts the pure sound by then reflecting, diffusing, absorbing, diffracting, dispersing, reshaping, and further dispersing this indirect sound energy, as illustrated in FIG. 1A by uncontrolled indirect speaker emitted sound IS.
Without adequate indirect sound control mechanisms, this uncontrolled indirect acoustic energy, that was originally a cohesive mass of acoustically-pure speaker-emitted indirect sound energy, is allowed, by default, to then return back to the listener's ears. At the listener's ears, after different, varying, and random first, second and third order reflections and diffusions, these sounds are heard as substantially distorted and corrupted out-of-sync indirect acoustic energy sounds and parts of sounds that can haphazardly intermix in confusing and negative ways with the speakers' direct sound component.
What is significant is that once this substantial quantity of originally acoustically-pure indirect sound is allowed to become corrupted, the substantial acoustic utility and value of its high-performance content are lost forever to the listener. What is lost is the original purity of the sound for the listener. This includes important acoustic components of the original sound presentation including the loss of individual spatial sound localizations, subtle acoustic nuances, important progressive time-delay cues, the original three-dimensional sound picture of the surrounding sound field, and the sound field's associated acoustically-pure natural reverberant energy component. Out-of-sync room reflections may include indirect sound problem and loss of important encoded acoustic information to the listener.
Another different, but severely-disruptive stereo audio listening room speaker-related acoustic problem that occurs with the smaller direct sound component is commonly referred to as direct sound stereo speaker “crosstalk”. In FIGS. 1A and 1B, direct sound stereo speaker crosstalk Lc is shown from the left conventional 60° projecting speaker to the listener's left and right ears. Stereo speaker crosstalk changes the direct sound component from the speakers above, into severely distorted and corrupted direct sound to the listener's ears and brain. Crosstalk is caused by the two or more stereo speakers projecting multiple parts of the same sound in direct uninterrupted straight lines to the two ears of a listener from two or more different speaker sound source locations. This is a very distorting to the human auditory system because it is an unnatural intermixing of multiple parts of the same sound hitting the listener's left and right ears from multiple directions. These multiple different directions of the same sound are also heard by the listener's two ears at slightly-different, but none-the-less disruptive, time-delay intervals. The result is that there are two, or even more, sound source locations for the one sound from the two or more speakers arriving at the listeners left and right ears in a straight uninterrupted path directly from the two or more different speaker locations.
These confusing multiple speaker crosstalk sounds from the direct sound component are then made substantially worse when they are also intermixed at the listener's ears with uncontrolled indirect sounds from the same two speakers that arrive to the listener's ears from a substantial plurality of uncontrolled, and variable directions, angles, and at different amplitude levels, frequencies, and progressive time-delay intervals. The total acoustic result for the listener is seriously acoustically-corrupted both direct and indirect sound that substantially interferes with and muddles-up the sound heard by the listener to the extent that what was originally acoustically-pure speaker-emitted sound has now become substantially corrupted sound to the listener's brain.
Introduction to Prior Art Acoustic Solutions
Listening rooms (e.g., high performance listening rooms) may include consumer and residential listening rooms; sound reproduction rooms; professional and commercial sound studios; retail audio equipment demonstration rooms, including speaker demonstration booths; meditation, stress management, behavior modification, health, fitness and wellness, and acoustic therapy facilities; audio-visual entertainment centers; and the like. Structurally, they usually require an acoustic room setup solution that typically includes a whole acoustically-preferential room or a substantial majority of the whole room. The rooms are to be acoustically sized, shaped, configured, and often need to be reserved, set-aside and are often greatly altered to enhance sound and surround sound.
High performance prior art listening room solutions often dictate highly restrictive, non-adjustable, or exclusive structural room placement of the speakers and the listener within a pre-set area at the center only portion of the listening room. This helps reduce and neutralize the acoustically-damaging negative effects of indirect sound emitted from speakers into the listening room. It is conventionally required that the stereo speakers and the listener not be placed in any other section or portion of a listening room. Speakers and/or listener are not to be positioned off to one side of a room, adjacent to windows, or near to an asymmetrical room configuration area of the listening room.
High performance prior art solutions structurally require, recommend or fundamentally expect the audio consumer to place a multiplicity of expensive, difficult-to-locationally position, and often high-energy consuming speakers, amplifiers, time-consuming extensive lengths of expensive special wiring installation, connective cables and a plurality of surround sound electronic equipment into the listening room to enhance sound and surround sound. This also conventionally requires extensive, time-consuming and cumbersome testing and trial-and-error speaker setup placement experimentation in order to determine the proper final speaker location(s) within the listening room.
One of the first and most important acoustic goals for high-performance sound and surround sound reproduction is to stay faithful to the original sound event and to limit compromising the original sound, limiting the amount of distortion, reproducing the highest fidelity in order for the listener to hear the audio signal without alteration. Electronic-based surround sound signal processing techniques, however, are not designed to reproduce the original signal without alternation. They are designed to compensate artificially for otherwise natural originally-localized surround sounds and surround sound fields. This is normally done either by artificial electronically manufactured surround sound or by artificially and electronically processing the original audio signal, often substantially.